Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income/(loss)	$ 12,722	$ (126)	$ 25,223	$ 1,894
Weighted average number of shares outstanding- basic (shares)	40,670,650	43,606,410	41,097,472	43,840,105
Effect of dilutive securities:
Total effect of dilutive securities (shares)	46,512	0	30,994	36,652
Weighted average number of shares outstanding - diluted (shares)	40,717,162	43,606,410	41,128,466	43,876,757
Basic earnings per share (usd per share)	$ 0.31	$ 0.00	$ 0.61	$ 0.04
Diluted earnings per share (usd per share)	$ 0.31	$ 0.00	$ 0.61	$ 0.04
Restricted stock awards
Effect of dilutive securities:
Effect of dilutive securities (shares)	7,449	0	7,236	5,138
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (shares)	25,095	0	15,789	3,393
Performance restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (shares)	0	0	0	3,700
Stock options
Effect of dilutive securities:
Effect of dilutive securities (shares)	13,968	0	7,969	24,421

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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